The need for anatomic models for medicinal science has been present since the advent of medicine, when Herophilus first used cadavers to train individuals. Currently, fresh, frozen, and fixed animal and/or human cadaveric tissues are used to educate and train individuals in anatomy and the medicinal sciences. However, these tissues may be anatomically different or possess differing mechanical properties to a living human patient.
Human skin is often categorized into thick skin, with a thickness of 400-600 μm, and thin skin, with a thickness of 75-150 μm. It is formed by a dermal layer, i.e. the dermis, formed of a highly vascularized network of collagen, elastin, fibronectin, and fibroblasts, an epidermal layer, of keratinocytes, melanocytes, Langerhans cells, Merkel cells, and a dermal-epidermal junction (basement membrane) between the epidermis and dermis. The skin can possess a stiffness of 185 N/m to 300 N/m, depending on area of the skin, hydration levels, age.
Anatomical reproductions and models are replacing cadavers for medical training. The need to practice surgical techniques has become increasingly important in the rapidly changing medical field. Artificial models provide advantages relative to cost, storage, reliability and shelf life. Furthermore, newer models account for differences in soft and hard tissue, allowing medical personnel to practice techniques using enhanced fidelity, and permits medical personnel to examine medical procedures and products, and how those procedures and products interact with a patient.
However, the majority of models will, at most, simulate the hard and soft tissue. However, some tissues, such as skin, possess varying characteristics throughout the various layers of the tissue. This limits the usefulness of such models, as the manipulation (i.e., scoring, cutting, moving, clamping, etc.) performed on the model fails to realistically simulate living tissue. Further, many models are not durable, and must be replaced at a high frequency. For example, Zeeff (U.S. Pat. No. 7,322,826) developed a soft tissue model formed of a nylon core material and a polyurethane cladding, which has limited elasticity due to the nylon core. The core and cladding are optionally attached as a bone or modeled bone, or configured to simulate a tendon. The model can be dyed for enhanced realism Additionally, current models used for practicing surgical techniques, also known as suture pads, are typically made from silicone or silicone and foam rubber. Suturing the material can be challenging as the silicone and foam tears easily upon pulling the sutures tight and through multiple uses. Examples of current suture pads include Smooth-on suture pads, such as various silicone products sold under the EcoFlex mark like EcoFlex 00-30 and EcoFlex Gel, silicon, silicon and latex, or silicone and foam models offered by 3-Dmed, as well as models from Simulab, Simvivo, Syndaver, Surgireal. Such high model turnover drastically increases the costs of training, as well as causing inferior training as the model ages through use.
As such, what is needed is a model that can realistically simulate the weight and consistency of soft tissues, while providing a durable product to limit the high turnover associated with most current models.